/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.coyote.http11.filters;

import org.apache.coyote.InputBuffer;
import org.apache.coyote.Request;
import org.apache.coyote.http11.InputFilter;
import org.apache.tomcat.util.buf.ByteChunk;

import java.io.IOException;
import java.nio.charset.Charset;

/**
 * Void input filter, which returns -1 when attempting a read. Used with a GET,
 * HEAD, or a similar request.
 *
 * @author Remy Maucherat
 */
public class VoidInputFilter implements InputFilter {


	// -------------------------------------------------------------- Constants

	protected static final String ENCODING_NAME = "void";
	protected static final ByteChunk ENCODING = new ByteChunk();


	// ----------------------------------------------------- Static Initializer

	static {
		ENCODING.setBytes(ENCODING_NAME.getBytes(Charset.defaultCharset()), 0,
				ENCODING_NAME.length());
	}


	// ----------------------------------------------------- Instance Variables


	// --------------------------------------------------- OutputBuffer Methods

	/**
	 * Write some bytes.
	 *
	 * @return number of bytes written by the filter
	 */
	@Override
	public int doRead(ByteChunk chunk, Request req)
			throws IOException {

		return -1;

	}


	// --------------------------------------------------- OutputFilter Methods

	/**
	 * Set the associated request.
	 */
	@Override
	public void setRequest(Request request) {
		// NOOP: Request isn't used so ignore it
	}

	/**
	 * Set the next buffer in the filter pipeline.
	 */
	@Override
	public void setBuffer(InputBuffer buffer) {
		// NOOP: No body to read
	}

	/**
	 * Make the filter ready to process the next request.
	 */
	@Override
	public void recycle() {
		// NOOP: Nothing to recycle
	}

	/**
	 * Return the name of the associated encoding; Here, the value is
	 * "void".
	 */
	@Override
	public ByteChunk getEncodingName() {
		return ENCODING;
	}

	/**
	 * End the current request. It is acceptable to write extra bytes using
	 * buffer.doWrite during the execution of this method.
	 *
	 * @return Should return 0 unless the filter does some content length
	 * delimitation, in which case the number is the amount of extra bytes or
	 * missing bytes, which would indicate an error.
	 * Note: It is recommended that extra bytes be swallowed by the filter.
	 */
	@Override
	public long end()
			throws IOException {
		return 0;
	}

	/**
	 * Amount of bytes still available in a buffer.
	 */
	@Override
	public int available() {
		return 0;
	}

}
